title: THIK-1 (K2P13.1) is a small-conductance background K(+) channel in rat trigeminal ganglion neurons.
abstract: The goal of this study was to determine the molecular identity of a small-conductance (~5-pS) background K(+) channel expressed in trigeminal ganglion (TG) neurons. We tested the hypothesis that the 5-pS channel is a K2P channel by comparing the pharmacological and single-channel properties of THIK-1 expressed in HEK293 cells. As reported earlier, whole-cell THIK-1 current was inhibited by halothane and activated by arachidonic acid. Among 25 additional modulators tested, bupivacaine (100 μM), quinidine (50 μM) and Ba(2+) (3 mM) and cold (10 °C) were most effective inhibitors of THIK-1 current (>50 % inhibition). In cell-attached patches with high KCl in the pipette and bath solutions, THIK-1 produced a small-conductance (~5 pS) channel with a weak inwardly rectifying current-voltage relationship. Halothane, bupivacaine and cold inhibited the single-channel activities of both THIK-1 and the 5-pS channel in TG neurons, whereas arachidonic acid augmented them. THIK-1 expressed in HEK293 cells and the 5-pS channels in TG neurons were insensitive to hypoxia. Reverse transcriptase-PCR, Western blot and immunocytochemical analyses suggested that THIK-1 mRNA and protein were expressed in TG neurons. These results show that THIK-1 is functionally expressed in TG neurons and contributes to the background K(+) conductance.
authors.affiliation: Department of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL, 60064, USA.
authors.forename: Dawon
authors.initials: D
authors.lastname: Kang
authors.forename: James O
authors.initials: JO
authors.lastname: Hogan
authors.forename: Donghee
authors.initials: D
authors.lastname: Kim
mesh_terms: D000200:Action Potentials; D000818:Animals; D015687:Cell Hypoxia; D002478:Cells, Cultured; D057809:HEK293 Cells; D006801:Humans; D009474:Neurons / Q000378:metabolism* / Q000502:physiology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024683:Potassium Channels, Tandem Pore Domain / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D012668:Trigeminal Ganglion / Q000166:cytology / Q000378:metabolism*
chemical_list: C430725:Kcnk13 protein, rat; D026902:Potassium Channel Blockers; D024683:Potassium Channels, Tandem Pore Domain; D012333:RNA, Messenger